I think it's an excellent idea to look at other reviews that have been published. After teaching myself statistics, I had to look at original papers in journals to find out the best way of presenting them as I hadn't got a clue. Using other reviews for form and style is extremely useful and I would suggest focusing on reviews of everything but the topic you're doing - that way you can't even unintentionally plagiarise.
As for searching, I always start with the BMJ and work from there. Just make sure you keep your search really narrow and specific.
The way I do all this definitely works - I had a paper published in the BJGP in November 06.
Good luck!
